Neuronal G protein-gated inwardly-rectifying K+ (GIRK) channels mediate the postsynaptic inhibitory effect of many neurotransmitters in the CNS and are implicated in nociception, analgesia, anxiety, seizure disorders, and addiction. Evidence suggests that an active process of compartmentalization promotes efficient and selective coupling of GIRK channels to appropriate G protein-coupled neurotransmitter receptors in vivo. The goal of my research is to identify the mechanism of compartmentalization that facilitates the functional relationship between GIRK channels and G protein-coupled receptors. I propose a multidisciplinary study that probes the functional interaction occurring between GIRK channels and the metabotropic gamma-aminobutyric acid (GABA) receptor, GABAB. In Aim #1,1 will use a recombinant expression strategy involving wild-type and chimeric GIRK subunits and cultured hippocampal neurons from GIRK knockout mice to identify the structural element(s) promoting the functional interaction between GIRK2-containing channels and GABAB receptors. The hypothesis to be tested is that a structural element in the carboxyl-terminal domain of a prevalent neuronal GIRK2 splice isoform promotes the functional association between GIRK channels and GABAB receptors in hippocampal neurons. In Aim #2,1 will use a chemical disruption strategy and electrophysiology to probe the impact of lipid raft disruption on the GABAB- GIRK signaling in hippocampal neurons. The hypothesis to be tested is that the co-sequestration in lipid rafts underlies the robust functional coupling observed between GIRK2-containing channels and GABAB receptors. Altogether, this work will yield new and important information about the subunit composition of native GIRK channels, the structural elements promoting strong and specific functional interactions between GIRK channels and G protein-coupled receptors, and the mechanisms used by neurons to compartmentalize molecules with related functions. A clearer understanding of the mechanisms that facilitate interactions between receptors and GIRK channels may suggest novel and more selective therapeutic approaches for the management of pain or treatment of addiction and neurological disorders. Relevance to public health: Most clinical drugs acting on the central nervous system evoke both beneficial and undesirable effects in patients. The premise of the research proposed herein is that by understanding how drugs act at the molecular level, we will be in a position to develop new drugs that can be used to more selectively and safely manage pain and mood disorders, or treat addiction.